MICE: The Trackers and Magnets Melissa Uchida Imperial College - PowerPoint PPT Presentation

MICE: The Trackers and Magnets Melissa Uchida Imperial College London NuFACT 2015

What is Muon Ionisation Cooling? ● A muon beam loses both transverse and longitudinal momentum by ionisation when passed through an `absorber' ● The lost longitudinal momentum is then fully/partially restored by RF cavities. ● The result is a beam of muons with reduced transverse momentum. RF Absorber Muon Accelerating (Liquid Momentum Cavity Hydrogen) ● However, this process also causes some heating due to multiple scattering so the net cooling is a delicate balance between these two effects: Melissa Uchida NuFACT 2015 2

Motivation: Summary ● Muon colliders and neutrino factories are attractive options for future facilities aimed at achieving the highest lepton-antilepton collision energies and precision measurements of parameters of the Higgs boson and the neutrino mixing matrix. ● Performance and cost depends on how well a beam of muons can be “cooled”. ● MICE has developed and will test a full or partial cooling cell, a series of which would be used to produce the collider or neutrino factory. ● Short lifetime of muon means that – traditional beam cooling techniques which reduce emittance cannot be used. – ionisation cooling is the only practical solution to preparing high intensity muon beams for use in these facilities. ● MICE is currently the only experiment studying ionisation cooling of muons. ● Recent progress in muon cooling design studies and prototype tests nourishes the hope that such facilities can be begin to be built during the next 20 years. Melissa Uchida NuFACT 2015 3

MICE Step IV ● Includes the two solenoidal spectrometers, a pair of alternating focus coils (field flips at centre), and an absorber (liquid-hydrogen, lithium-hydride etc); ● allows normalised emittance change of beam passing through an absorber to be measured (before and after the absorber by the Trackers), ● over a range of momenta and under a variety of focusing conditions. ● However, it will lack the crucial RF re-acceleration required for “sustainable” cooling (lost energy is not restored hence cooling cannot be iterated). ● Data taking for calibration and commissioning has begun!!! Melissa Uchida NuFACT 2015 4

MICE: Demonstration of Ionisation Cooling (2017) ● The cooling section contains one full absorber, plus two secondary absorbers which protect the tracking devices from radiation emitted by the RF cavities and also increase the measured cooling factor. ● The baseline magnetic configuration of the cooling section is referred to as “FOFO” and is such that the magnetic field reverses (“flips”) at the centre of the central absorber. ● Periodic field reversal is essential for a full-length cooling channel in order to prevent growth of canonical angular momentum. Melissa Uchida NuFACT 2015 5

The Detectors – Time Of Flight: TOF0, TOF1 and TOF2 – Electron Muon Ranger: EMR – KLOE-Light: KL – Cerenkov: CkoVa CkoVb – – – Trackers ● 2 Tracker detectors upstream and downstream of cooling section, each immersed in a uniform magnetic field of 4T. ● Measure the normalised emittance precision to 0.1% (beam emittance measured before and after cooling). Melissa Uchida NuFACT 2015 6

The Trackers ● Two scintillating fibre trackers, one upstream, one downstream of the cooling channel. ● Each within a spectrometer solenoid producing a 4T field. ● Each tracker is 110 cm in length and 30 cm in diameter. ● 5 stations ● varying separations 20-35 cm (to determine the muon pT). ● 3 planes of fibres per station each at 120°. ● LED calibration system. ● Hall probes. Melissa Uchida NuFACT 2015 7

The Trackers ● 350 μm scintillating fibres are glued into doublet layers (planes) ● Thickness: 627μm (a). ● 7 fibres are grouped into a single readout channel (b). (This reduces the number of readout channels, while maintaining position resolution). ● Position resolution: 470 μm. Melissa Uchida NuFACT 2015 8

Tracker Installation Trackers are sensitive to light < 450 nm.... Melissa Uchida NuFACT 2015 9

Tracker Installation Melissa Uchida NuFACT 2015 10

Tracker Installation Melissa Uchida NuFACT 2015 11

Tracker Installation Melissa Uchida NuFACT 2015 12

Tracker Installation Melissa Uchida NuFACT 2015 13

In The MICE Hall Melissa Uchida NuFACT 2015 14

Tracker Readout ● Light carried from trackers via external waveguides (lightguides). – 1 mm clear fibres. – 152 fibres per waveguide. – 13 waveguides per cryostat. ● Fibres readout by Visible Light Photon Counters – operating at liquid He temperatures. ● Digitised by FPGA based system from D0. Melissa Uchida NuFACT 2015 15

Tracker Commissioning Hits in the 3 Planes of Stn 1 UST Mid-Commissioning Dead channels and electronics problems are identified and corrected by considering low level reconstruction objects eg hits. Melissa Uchida NuFACT 2015 16

US Tracker Commissioning Nearest to absorber Mid-Commissioning Melissa Uchida NuFACT 2015 17

DS Tracker Commissioning Nearest to absorber Mid-Commissioning Melissa Uchida NuFACT 2015 18

Sum of Channels Hit Mid-Commissioning Should add up to 318 → indicates the waveguide/channel mapping is accurate. Melissa Uchida NuFACT 2015 19

Pe in Upstream Tracker Melissa Uchida NuFACT 2015 20

Tracker Data First Tracks! (No field) Melissa Uchida NuFACT 2015 21

Tracker Alignment (Kalman) PRELIMINARY Melissa Uchida NuFACT 2015 22

Tracker Alignment (Kalman) PRELIMINARY Melissa Uchida NuFACT 2015 23

Tracker Data First Helical Tracks! Reconstructed spacepoints showing a particle making a helical trajectory in the Downstream Tracker Melissa Uchida NuFACT 2015 24

● Two Spectrometer solenoids. The ● Produce a 4 T magnetic field. Magnets ● 5 coils in each spectrometer solenoid: ● Central coil which covers the Trackers. ● 2 end coils either side of the central coil. ● 2 matching coils nearest the absorber. Not to ● All coils wound onto the same bobbin. scale ● Core temperature 4 K. ● Operating pressure 1.5 bar. ● Absorber focus coil (surrounding absorber). ● flip/non-flip mode, from 2 coils. Melissa Uchida NuFACT 2015 25

The Magnets Not to scale Melissa Uchida NuFACT 2015 26

MEASUREMENT OF THE MAGNETIC AXIS SSU, SSD, FC2 AND FC1 Melissa Uchida NuFACT 2015 27

Thanks to Victoria Blackmore Magnet Alignment Survey point Coil Bellows Reference particle Melissa Uchida NuFACT 2015 28

Thanks to Victoria Blackmore CERN Field Mapper Rails Trolley with B-sensors ¼ pipe of aluminum Cradles Service module Tooth belt Servo motor with encoder Melissa Uchida NuFACT 2015 29

Thanks to Victoria Blackmore CERN Field Mapper CERN Mapper in FC2 Melissa Uchida NuFACT 2015 30

Thanks to Victoria Blackmore Magnet Alignment Survey point Coil B , a r B z , a Melissa Uchida NuFACT 2015 31

Thanks to Victoria Blackmore Method 1 Field Mapper Axis Points don’t go through , so mapper is not on ) magnetic axis Melissa Uchida NuFACT 2015 32

Thanks to Victoria Blackmore Method 2 ● Look at the transverse field vectors. • vectors point to the magnetic axis. • Lines along the transverse field vectors measured by all Hall probes at one z (970mm in mapper coordinates) Best fit vertex Plots are SSD data Melissa Uchida NuFACT 2015 33

SSU Measured vs Calculated field Melissa Uchida NuFACT 2015 34

Magnet Alignment ● We have measured the positions of the magnetic axes to < 1 mm. ● Data taken with only SSD powered – Cross check magnetic analysis with beam – Preliminary result is consistent with magnetic analysis ● 'Correcting' bellows may be constructed for the Demonstration of Ionisation Cooling, to improve the magnetic axis alignment further. Thanks to Victoria Blackmore Melissa Uchida NuFACT 2015 35

Magnet Readiness ● All magnets are fully tested and have been individually trained (outside of the MICE experimental hall). ● All magnets are installed. ● Magnet training in situ has begun. ● Magnet training is due to be complete in the next few months. Melissa Uchida NuFACT 2015 36

Conclusions ● MICE has two Tracker detectors to measure the beam emittance before and after cooling. ● The Trackers are installed, QA'd and cosmics tested. ● Calibration and commissioning is well underway and is going well. ● Data taking has started: – Straight tracks for alignment. – Tracks with field on (during magnet training). ● Two superconducting solenoids surround the Trackers and an Alternating focus coil magnet around the absorber. ● All magnets are tested and installed. ● Magnet training is currently in progress. Melissa Uchida NuFACT 2015 37